The need for emission-free joints has become more urgent in recent years in the exhaust systems of internal combustion engines due to requirements of state and federal environmental agencies. Increased consciousness of public health is another factor that has made such joints more desirable to users of engines. The telescoped pipes of exhaust systems are required to be connected between the engine and the muffler or between the engine and a catalytic converter for example in such a way that there is not escape of gas from the system except where intended.
One general approach is the use of accurately engaged pipes held together with suitable clamps. This is an expensive approach and it relies upon the system being maintained in an undisturbed condition. It also depends upon the accuracy of the engaged shapes not being modified during handling and installation. U.S. Pat. No. 3,788,677 is an example of such systems and explains some of the problems.
Another approach is one in which a U-bolt clamp is used and tightened with such force that the telescoped tubing of a joint is literally crimped or crushed together due to the necking of the tubing. The invention herein is concerned with the latter approach.
The U-bolt clamps of the prior art for the most part use the same type of U-bolt, the differences being in the construction of the saddle. Various schemes have been proposed which require complex tools and dies, which require welding or other expensive processes for assembly, or which provide devices that may not withstand the great application of force needed to crush the tubing of the joint. Examples of the prior art are the following U.S. Pat. Nos.:
3,137,053 -- Osborn et al PA1 3,772,745 -- Dowling et al PA1 3,340,581 -- Engman PA1 2,959,834 -- Graham
The invention is characterized by the construction of a saddle made out of two sheet metal members formed by stamping, identical in all respects but for the presence of a tab along the top edge of one member. The members are reversed relative to one another, placed in a suitable die face to face and assembled by bending end flanges and the tab onto one another. No other means of attachment such as fastening devices or welding are used and yet the structure resulting is robust and effective for the purposes designed.
A rib upset in each sheet metal member and arranged transverse of the line of bending during use resists such bending moment.